Convert optional-dependencies to dependency-groups (#220)

The dev and test dependencies are not meant for external use; as such,
they make more sense as dependency groups than as extras.

See also: marshmallow-code/webargs#1039

Author: sirosen

pyproject.toml

@@ -24,9 +24,10 @@ Issues = "https://github.com/marshmallow-code/marshmallow-oneofschema/issues"
 Funding = "https://opencollective.com/marshmallow"
 Source = "https://github.com/marshmallow-code/marshmallow-oneofschema"
 
-[project.optional-dependencies]
+[dependency-groups]
 tests = ["pytest"]
-dev = ["marshmallow-oneofschema[tests]", "tox", "pre-commit>=3.5,<5.0"]
+dev = [{include-group = "tests"}, "tox", "pre-commit>=3.5,<5.0"]
+
 
 [build-system]
 requires = ["flit_core<4"]

tox.ini

@@ -7,7 +7,7 @@ envlist=
     py39-lowest
 
 [testenv]
-extras = tests
+dependency_groups = tests
 deps =
     marshmallow3: marshmallow>=3.0.0,<4.0.0
     marshmallow4: marshmallow>=4.0.0,<5.0.0